1. Field of the Invention
This invention relates to a method of manufacturing an EL (Electro Luminescence) device.
This application is based on Patent Application No. Hei 9-324088 filed in Japan, the content of which is incorporated herein by reference.
2. Background Art
Recently, new methods have been proposed to apply laser machining in manufacturing organic EL devices. For example, a method, shown in FIG. 6, is disclosed in Japanese Patent Application, First Publication No. Hei 9-50888.
This method first forms a transparent anode 102 on a surface of a transparent glass substrate, as shown in FIG. 6A, and then forms a laser protective layer 103, which is an insulating layer, excluding pixel areas for forming pixels 108, as shown in FIG. 6B. Subsequently, after a luminescence layer 104 made of an organic material and a cathode material layer 105 are formed by vacuum deposition, as shown in FIG. 6C, the cathode 106 is formed by evaporating a part of the luminescence layer 104 and the cathode layer 105 included in the laser machining portion 107 by irradiating from the top of the laser machining portion 107 a laser light emitted by a YAG laser or an excimer laser; and thereby an organic EL device having a plurality of pixels corresponding to the pixel areas is formed.
Another manufacturing method is shown in FIG. 7. This method first forms a transparent anode 102 on a surface of a glass substrate 101 (FIG. 7A), forms a luminescence layer 104 made of an organic material and a cathode material layer 105 successively by vacuum deposition (FIG. 7B), and forms a laser absorption layer 109, the surface of which has a lower reflectance than that of the cathode material (FIG. 7C). Subsequently, after forming a laser absorption layer 109, a cathode 106 is formed by evaporating the laser machining portion and the cathode layer by irradiating from the top of the laser machining portion 107 a laser light emitted by a YAG laser or an excimer laser to obtain an organic EL device having a plurality of pixels corresponding to pixel areas.
The other method of manufacturing the organic EL device is shown in FIG. 8. In this method, a transparent anode is formed on a transparent glass substrate 101 (FIG. 8A), and a laser protective layer 103 is formed thereon with the exception of areas for forming pixels 108 (FIG. 8B). A luminescence layer 104 made of an organic material and a cathode material layer 105 are successively formed by vacuum deposition (FIG. 8C). After forming a laser absorption layer 111, the surface of which has lower reflectance than the cathode material layer (FIG. 8D), the luminescence layer 104 and the cathode material layer 105 are removed by evaporation by irradiating from the top of the laser machining portion 107 a laser light of a YAG laser or an excimer laser to form the cathode 106 (FIG. 8E); thereby, an organic EL device having a plurality of pixels 108 corresponding to pixel areas is obtained.
In the above described conventional manufacturing methods disclosed in Japanese Patent Application, First Publication No. Hei 9-50888, a problem has been encountered that chips of metal generated by laser machining of the electrode stick again to the surface of the laser machined area, causing short circuits between electrodes and reducing the yield of production.
It is therefore an object of the present invention to provide a method of manufacturing organic EL devices at a high yield by preventing short circuits between electrodes.